[1] He became politically active when he joined the Workers International Industrial Union in 1915 while working at the William Beardmore and Company shipyard, in Dalmuir.
The following year, he was elected as the first communist councillor in Clydebank, although he resigned in 1937 to move to London and become National Industrial Organiser for the CPGB.
He also held various District Secretary posts for the party: Scotland in 1935, the North Midlands from 1939 to 1940, and South Yorkshire from 1940 to 1942.
[3] Hart stood for parliament on three occasions, West Dunbartonshire in 1950, and Glasgow Springburn in 1955 and 1959, but was never elected.
He retired from his party posts in 1963, but later became Provost of Clydebank[4] and participated in the Upper Clyde Shipbuilders work-in.